Simulation and Experiment of Mass Evacuation to a Tsunami Evacuation Tower

A 3D mass evacuation simulation using precise kinematic digital human (KDH) models and an experimental study are discussed. The tidal wave associated with the large tsunami caused by the Great East Japan Earthquake was responsible for more than 90% of the disaster casualties. Unfortunately, it is expected that other huge tsunamis could occur in Japan coastal areas if an earthquake with magnitude greater than 8 occurred along the Nankai Trough. Therefore, recent disaster prevention plans should include evacuation to higher buildings, elevated ground, and construction of tsunami evacuation towers. In the evacuation simulation with 500 KDHs, the mass consists of several subgroups. It is shown that the possible evacuation path of each group should be carefully determined to minimize the evacuation time. Several properties such as evacuee motion characteristics of KDHs, number of evacuees, exit gates and, number of injured persons were carefully considered in the simulation. Evacuee motion was also experimentally investigated by building a test field that simulates the structure of an actual tsunami evacuation tower for accommodating approximately 120 evacuees. The experimental results suggest that an appropriately divided group population may effectively reduce the overall group evacuation time. The results also suggest that the fatigue due to walking during evacuation adversely affect the total evacuation time, especially the ascent of stairways. The experimental data can be used to obtain more accurate simulations of mass evacuation.

Atomic Force Microscopy of Annealed Plain Carbon Steels

Microstructure of annealed plain carbon steels is examined using optical microscopy. When the inter-lamellar spacing in pearlite is small, optical microscope at 1000X is unable to resolve the ferrite and cementite lamellae. In hyper-eutectoid steels, cementite in pearlite appears as darker phase whereas the pro-eutectoid cementite appears as a lighter phase. Atomic force microscopy (AFM) of etched steels is able to resolve ferrite and cementite lamellae in pearlite at similar magnifications. Both cementite in pearlite as well as pro-eutectoid cementite appear as raised areas (hills) in AFM images. Interlamellar spacing in pearlite increases with increasing hardenability of steel.

Kriging-Based Reliability Analysis and Variance-Based Sensitivity Analysis for an Idler Shaft

In order to analyze the reason of failure and improve the reliability of the idler shaft, this paper studies the reliability and sensitivity for the idler shaft based on Kriging model and Variance Methods respectively. The finite element analysis (FEA) of idler shaft is studied in ABAQUS firstly. Then, combining the performance function and various random variables, the Kriging model of idler shaft is established and verified. Based on Kriging model which has been established, the relationship between random variables and the response value is studied, and the function reliability is calculated which explains why the failure of the idler shaft occurred frequently in service. Finally, the variance-based sensitivity method is used for sensitivity analysis of influence factors, the result shows that the reliability of idler shaft is sensitive to the inner diameter of body A and inner diameter of body B, which could contribute for the analysis and further improvement of idler shaft.

A Stochastic Asset Life Prediction Method for Large Fleet Datasets in Big Data Environment

Preventing catastrophic failures is the most important task of prognostics and health management approaches in industry where Remaining Useful Life (RUL) prediction plays a significant role to schedule required preventive actions. Regarding recent advances and trends in data analysis and in Big Data environment, industries with such foreseeing approach are able to maintain their fleet of assets more efficiently with higher assurance. To address this requirement, several physics-based and data-driven methods have been developed to predict the remaining useful life of various engineering systems. In current paper, we present a simple, yet accurate stochastic method for data-driven RUL prediction of complex engineering system. The approach is constructed based on selecting the most significant parameters from raw data by using the improved distance evaluation method as feature selection algorithms. Subsequently, the health value of units is assessed by logistic regression and the assessment output is used in a Monte Carlo simulation to estimate the remaining useful life of the desired system. During Monte Carlo iterations, several features are extracted to help filtering less accurate estimations and improve the overall prediction accuracy. The proposed algorithm is validated in two ways. First of all, the accuracy of RUL prediction is measured by applying the method to 2008 PHM data challenge gas-turbine dataset. Subsequently, gradual changes in RUL prediction of a particular test unit are measured to verify the behavior of the algorithm upon availability of additional historical data.

Effect of Condition Monitoring on Risk Mitigation for Steam Turbines in the Forest Products Industry

Industry has been implementing condition monitoring for turbines to minimize losses and to improve productivity. Deficient conditions can be identified before losses occur by monitoring the equipment parameters. For any loss scenario, the effectiveness of monitoring depends on the stage of the loss scenario when the deficient condition is detected. A scenario-based semi-empirical methodology was developed to assess various types of condition monitoring techniques, by considering their effect on the risk associated with mechanical breakdown of steam turbines in the forest products (FP) industry. A list of typical turbine loss scenarios was first generated by reviewing loss data and leveraging expert domain knowledge. Subsequently, condition monitoring techniques that can mitigate the risk associated with each loss scenario were identified. For each loss scenario, an event tree analysis was used to quantitatively assess the variations in the outcomes due to condition monitoring, and resultant changes in the risk associated with turbine mechanical breakdown. An application was developed following the methodology to evaluate the effect of condition monitoring on turbine risk mitigation.

Effect of Boron Nitride on the Mechanical and Electrochemical Properties of Cement Composite

Hexagonal boron nitride (h-BN) is well known for its unique properties, such as high thermal conductivity, excellent mechanical strength, high electrical insulating, and high chemical stability. This paper studies the effect of h-BN to the mechanical and electrochemical properties of cement concrete. Sodium cholate is used as an ionic surfactant to exfoliate h-BN and subsequently stabilize them in water solution. Different cement concrete samples with different doping levels of h-BN and different sizes of h-BN were prepared for comparisons. Also, steel fiber reinforced h-BN/cement concrete samples were also prepared. The results show that the addition of h-BN can improve the strength of cement composites, and the degree of reinforcement are influenced by the doping levels and feature size of h-BN. The corrosion resistance of h-BN/cement composites were also tested. Experiments results show that h-BN can enhance the corrosion resistance of cement composites.

Improving Dynamic Fault Tree Method for Complex System Reliability Analysis: Case Study of a Wind Turbine

Fault Tree Analysis (FTA) is one of the most developed techniques in reliability studies; however static analysis is not able to encompass the dynamic behavior of complex systems. To overcome this problem, Dynamic Fault Tree (DFT) analysis is suggested in recent researches. The main motivation of this study is a comparative study on differences between Static Fault Tree (SFT) and DFT models of a typical mechanical system (case study of a wind turbine). Also, this paper is aimed to interpretation of the results and sufficiency analysis of SFT to model this system. This study, first presents a SFT analysis for a wind turbine system. Then, DFT is developed for the system. Monte Carlo simulation based method is applied for its analysis. The comparison showed that the DFT method presents more useful and realistic model of a wind turbine system. The proposed method improved the analysis through modification of dynamic gates.

A Parametric Study of the Modeling of Orthogonal Machining Using the Smoothed Particle Hydrodynamics Method

Modeling machining processes with conventional finite element methods (FEM) is challenging due to the severe deformations that occur during machining, complex frictional conditions that exist between the cutting tool and the workpiece, and the possibility of self contact due to chip curling. Recently, the Smoothed Particle Hydrodynamics (SPH) method has emerged as a potential alternative for modeling machining processes due to its ability to handle severe deformations while avoiding mass and energy losses encountered by traditional FEM. The method has been implemented in several commercial finite element packages such as ABAQUS and LS-DYNA for solving problems involving localized severe deformations. Numerous control parameters are present in a typical SPH formulation. The purpose of this work is to evaluate the effect of the three most important parameters, namely, the smoothing length, particle density, and the type of SPH formulation. The effects of these parameters on the chip morphology and stress distribution in the context of orthogonal machining of AISI 1045 steel are investigated. The LS-DYNA finite element package along with Johnson-Cook material model is used for this purpose. Results from the parametric study are presented and compared with the previously reported results in the literature. In addition, the sensitivity of chip morphology and stresses to Johnson-Cook parameters for AISI 1045 steel is also investigated by considering five different sets of values reported in the literature for this steel.

Effect of Paper Property on Mechanical Property of Paper Tube

Paper recycling is an effective way in reducing deforestation and energy consumption. Therefore recycling paper and paper products has been widely applied in many areas, such as packaging industry, film rolls, adhesive-tape industry, furniture decoration and temporary structures in building. They can be produced into various structure according to different requirement, such as paper tube, corrugated paperboard and normal paperboard. Paper-tubes gain more and more applications as a traditional structure due to their excellent mechanical property and environmentally friendly property. In order to meet various needs of paper-tube and produce high performance paper-tubes, designing for paper-tubes fabrication is needed. It is necessary to research the lateral compression strength of paper tube because various paper-tubes are used as packages, cores, poles and structure materials. To establish a relation of mechanical property between paperboards and paper-tubes is an important aspect. The current study is to investigate this relation. Paperboards are built from cellulose fibers jointed by hydrogen bonds and some additional elements like talc. The fibers are distributed randomly on the paperboards. However due to the tension action during fabrication process, more fibers are distributed in machine rolling direction which is defined as machine direction (MD, TD for transverse direction). The material expresses obvious anisotropic property. On the other hand, due to the laminated structure of paper materials, it is possible to generate interlaminar fracture in the usage process, especially in the construction made of paper such as paper tubes. The mechanical property of three kinds of paperboards used for paper-tubes fabrication was investigated included tension, compression and peeling combining with anisotropic property. These three kinds of paperboards have different mechanical properties but same dimension for paper-tubes fabrications. By this method, the effects of different properties including tension, compression and peeling on mechanical property of paper-tube could be evaluated. A series of paper-tubes with different layers was fabricated and the lateral compression test was carried out and evaluated. The fracture form of paper-tubes and fracture position on paper-tube were discussed together with paperboards. The cause of delamination behavior of laminated paper was analysis based on the detailed observation. The optical observation were employed to evaluate the fracture properties of paper-tubes after lateral compression test. It was found that the initial fracture of paper-tubes occurred inside the paperboards rather than between layers and the peeling property of paperboard has a signification effects on lateral compression property of paper-tubes.

The Relationship Between Tensile and Fatigue Strength of Friction Welded Steel Joints

The friction welding of AISI 52100 grade low chromium and high carbon steel joints are investigated in this work to evaluate the fatigue life of the joints by conducting the experiments using servo hydraulic fatigue testing machine at different stress levels. All the experiments are conducted under uniaxial tensile loading condition (stress ratio=0). Fatigue strength, fatigue notch factor (Kf) and notch sensitivity factor (q) are evaluated for the optimized joints and the relationship between tensile and fatigue properties of Fully Deformed None (FDZ) is established. Finally, the Characteristics of friction welded joint is investigated with the help of Scanning Electron Microscope and Optical Microscopy under optimized condition.